Blade arrangement for a snowplow and the like

ABSTRACT

THE BLADE OF A SNOW PLOW IS PIVOTED ON THE ASSOCIATED VEHICLE FOR MOVEMENT ABOUT A HORIZONTAL AXIS, AND NORMALLY PREVENTED FROM PIVOTING BY A SPRING LOADED DETENT ON THE BLADE ENGAGING A LATCH PIN ON THE FIXED BLADE SUPPORT. WHEN THE LOWER EDGE OF THE BLADE HITS AN IMMOVABLE OBSTACLE, THE DETENT IS RELEASED, AND THE BLADE CAN YIELD. WHEN THE PLOW THEREAFTER IS BACKED UP, A SPRING RETURNS THE BLADE TO ITS NORMAL POSITION AND AUTOMATICALLY ENGAGES THE DETENT WITH THE LATCH PIN.

Dec- 14, 1971 Y A. KAHLBACHER 3,62

BLADE ARRANGEMENT FOR A SNOWPLOW AND THE LIKE Filed Dec. 18, 1969 2 Sheets-Shoot l Dec. 14, 1971 A. KAHLBACHER ,62,6

BLADE ARRANGEMENT FOR A SNOWPLQ-W AND THE LIKE l Filed Dec. 18, 1969 2 Sheets-Sheet E United States Patent 3,626,614 BLADE ARRANGEMENT FOR A SNOWPLOW AND THE LIKE Anton Kahlhacller, 8 Aschbachweg, 6370 Kitzbuhel, Tirol, Austria Filed Dec. 18, 1969, Ser. No. 886,422 Claims priority, appliatgrlgAustria, Jan. 2, 1969,

Int. Cl. A01b 6]/00 U-S. Cl. 37-42 VL 8 Claims ABSTRACT OF THE DISCLOSURE The blade of a snow plow is pivoted on the associated vehicle for movement about a horizontal axis, and normally prevented from pivoting by a spring loaded detent on the blade engaging a latch pin on the xed blade support. When the lower edge of the blade hits an immovable obstacle, the detent is released, and the blade can yield. When the plow thereafter is backed up, a spring returns the blade to its normal position and automatically engages the detent with the latch pin.

This invention relates to a blade arrangement for a snow plow, bulldozer, or similar material-moving apparatus, and particularly to a device for protecting the blade against damage by an immovable obstacle.

The invention will be described hereinafter with reference to a vehicular snowplow in which the invention has particular utility, but its advantages in a bulldozer or other material moving apparatus will readily be apparent.

It is common practice to provide the blade assemblies of snowplows with shearpins releasing the blade of the plow when the blade hits an obstacle not capable of being moved by a force for which the blade is designed. It has also been proposed to mount the blade on springs which yield when the blade is subjected to excessive operating stresses. Torsion bars have been employed for the same purpose.

Shear pins perform in a precisely predictable manner, but a broken shear pin cannot be replaced without interrupting the operation of the snowplow for a relatively long period. The load at which a conventional spring releases the blade is not accurately predictable, and it changes during the normal service life of the spring, particularly after the spring has been deformed repeatedly by overloads applied to the blade.

A primary object of the invention is the provision of an overload release mechanism for the blade of a `snowplow or like material handling apparatus which responds to precisely predictable and adjustable stresses applied to the blade, which can be restored to its normal operating condition by the plow operator in a matter of seconds without leaving his cab, and whose performance is not affected by repeated overloads.

With this object and others in View, as will presently become apparent, the invention provides an arrangement in which the -blade is secured to its support for angular movement about a pivot axis extending in a common direction with the operating face of the blade. An overload-responsive releasable latch device normally prevents angular movement of the blade about the pivot axis under the pressure of the engaged snow.

The latch device includes a latch pin mounted on the blade support and a detent-carrying arm mounted on the blade. A helical compression spring normally biases the detent toward engagement with the pin, but the arm is movable in response to excessive snow pressure toward a released position in which it clears the pin, the spring opposing such movement.

3,626,614 Patented Dec. 14, 1971 "ice Other features, additional objects, and many of the attendant advantages of this invention will readily be appreciated as the same becomes better understood by reference to the following detailed description of a preferred embodiment when considered in connection with the appended drawing in which:

FIG. 1 shows a snowplow equipped with the blade arrangement of the invention in fragmentary side-elevation;

FIG. 2 shows a portion of the apparatus of FIG. l in side-elevational section on a larger scale;

FIG. 3 shows another portion of the apparatus of FIG. l in side-elevation and partly in section on the scale of FIG. 2;

FIG. 4 shows the device of FIG. 2 in plan View; and

FIG. 5 is a plan view of the device of FIG. 3.

Referring now to the drawing in detail, and initially to FIG. 1, there is seen the blade 1 of a vehicular snowplow whose forwardly directed operating face is approximately cylindrically concave about a horizontal axis in the illustrated, normal, operating condition of the apparatus. Stiening ribs 2 fixedly attached to the convex rear face of the blade 1 pivotally fasten the same to a cylindrical shaft 3 whose axis 4 is normally horizontal and transverse to the direction of snowplow movement. A main supporting bracket 5 is fixedly attached to the shaft 3 and can pivot about a vertical axis on the partly illustrated frame 28 of the tractor or other automotive vehicle carrying the blade arrangement and not otherwise shown.

Two radial arms 6 of steel plate tixedly attached to the shaft 3 extend upwardly from the shaft, and their free ends are fixedly connected by a latch pin 7, as is best seen in FIGS. 2 and 4. A sleeve 27 axially secured between the arms 6 provides a freely rotatable facing on the central, cylindrical portion of the pin 7.

In the illustrated condition of the apparatus, the latch pin 7 cammingly cooperates with a detent 30 transversely projecting from an arm 8, the arm being connected with the blade 1 by a bar 9 attached to the rear face of the blade 1. As is shown in more detail in FIGS. 3 and 5, a bracket 10 approximately U-shaped in section transversely to the bar 9 is xedly fastened to the free end of the bar. The arm 8 is pivoted on a pin 11 which passes horizontally through the upright flanges of the 'U-shape.

The lower, longitudinal face .12 of the arm 8 is flat and tangential to the sleeve 27 from the pivot pin l11 to a cylindrically arcuate, concave side face of the detent 30 which conformingly engages the facing sleeve 27 of the pin 7 in an arc of only slightly more than 90=. Another cam face portion 13 of the detent 30 is angularly offset from the side face. The Cam face portion 13 is ilat and obliquely inclined to the direction of elongation of the arm.

The arm 8 may pivot on the pin 11 until its movement away from the illustrated position of longitudinal alignment with the bar 9 is stopped by abutting engagement with the web portion 14 of the bracket .10x Movement of the pin 7 and arm 8 relative to each other away from the illustrated position is opposed and normally prevented by a helical compression spring 16 stressed by abutment between a receptacle 15 dixedly attached to the free end of the arm 8 and a receptacle 17 hingedly fastened to the bracket 10` by a pivot pin 26 parallel to the pin 1.1. The axes of the pins 11, 26 are spaced from each other transversely of the common direction of elongation of the arm 8 and the bar 9 so that the spring 16 tends to pivot the arm 8 clockwise on the pin 1.1, as viewed in FIG. 1, and toward abutting engagement with the latch pin 7. The length, and therefore the initial stress of the spring 16 may be adjusted by means of an abutment screw 18 ou the receptacle 15.

The reinforced top edge 19 of the blade 1 carries an apertured lug in a common plane perpendicular to the pivot axis 4 with a similar lug 21 on the main supporting bracket 5. A tension spring 2-2 connects the lugs 20, 21 and is almost fully relaxed in the position shown in FIG. 1. The lower horizontal edge of the blade 1 is reinforced by a at scraping bar -2'3 as is conventional.

In the illustrated normal operating condition of the blade arrangement, the spring 22 hangs loosely between the two lugs 20, 21, and the arm 8 and detent 30 abuttingly engage the pin 7 under the biasing force of the spring 16. When the scraping bar 23 on the moving plow hits an immovable obstacle, such as the curb of a sidewalk, a force is suddenly applied to the bar 23 in the direction of the arrow 24 (FIG. l). The impact causes the detent 30 to slip over the oblique cam face of the pin 7 sufficiently to clear the pin and to permit pivoting movement of the blade 1 on the shaft 3 in the counterclockwise direction of the arrow 25. The cam face 13 of the detent 30 is held in contact with the pin 7 by the spring 16 as far as abutting engagement of the arm 8 with the web 14 permits, while the blade 1 is being pivoted and the spring 22 is being tensioned.

When the operator reversed the direction of movement of the plow or raises the blade arrangement in a conventional manner, not illustrated, until the blade 1 clears the obstacle, the spring 22 returns the apparatus to the illustrated position, the pin 7 sliding along the guiding cam face 13 of the detent 30 until it drops behind the detent 30. The face 13 is inclined at a small acute angle relative to the axis of the compression spring 16 so that the spring 22 can overcome the resistance of the spring 16 during the return movement.

It will be appreciated that the illustrated latch arrangement may be modied by permutation of the latch members and of their modes of operation without departing from the spirit of the invention. Thus, the arm 8 may be iixed on the blade .1, and the pin 7 be longitudinally slidable on the arms 6. The pin 7 may be mounted on the blade 1 and the arm 8 on the supporting structure. Ultimately, both latch members may be movably mounted. Only minor changes are needed for locating the latch mechanism below the pivot axis 4 without changing the functioning of the device, and other variations will readily suggest themselves to those skilled in the art, the illustrated embodiment being preferred at this time for its reliability in operation and convenience in manufacture.

What is claimed is:

1. VIn a blade arrangement for a snowplow having a support, a blade member having an operating face, pivot means securing said blade member to said support for angular movement about a iirst pivot axis toward and away from an operative position, and overload-responsive releasable latch means for holding said blade member in said operative position and for releasing the blade member from said position in response to a predetermined force exerted on said face, the improvement in the latch means which comprises:

(a) a pin member mounted on said support;

(b) an elongated arm having two end portions, one end portion being mounted on said blade member for pivoting movement about a second pivot axis;

(c) a detent on the other end portion of said arm; and

(d) yieldably resilient means holding said detent in engagement with said pin member and thereby impeding movement of said blade member away from the operative position, said yieldably resilient means including (l) two abutments secured to said blade member 4 member and to said other end portion respectively, said abutments being laterally offset from said arm and spaced from each other in the direction of elongation of said arm, and (2) a helical compression spring interposed between said abutments.

2. In an arrangement as set forth in claim 1, a bar member fixed on another face of said blade member opposite to said operating face and elongated in a direction away from said other face, bracket means on said bar member remote from said other face, said one end portion being mounted on said bracket means for said movement thereof about said second axis, and one of said abutments being mounted on said bracket means for pivoting movement about a third axis spaced from said second axis transversely to the direction of elongation of said arm.

3. In an arrangement as set forth in claim 2 adjusting means for moving one end of said spring with respect to said one abutment.

4. In an arrangement as set forth in claim 1, biasing means connecting said blade member to said support and biasing said blade member toward said operative position thereof, said detent having two angularly offset cam faces, one of said cam faces engaging said pin member in said operative position of the blade member and said pin member engaging the other cam face during movement of the blade member toward and away from said operative position, said yieldably resilient means urging said other cam face into engagement with said pin member.

5. In an arrangement as set forth in claim 4, said arm having two opposite longitudinal faces, one of said abutment member being secured to one of said longitudinal faces, and said detent projecting from the other longitudinal face.

6. 'In an arrangement as set forth in claim 4, said one cam face being arcuate, and said pin member having an engagement face held in contact with said one cam face over an arc of not substantially more than 7. In an arrangement as set forth in claim l, said blade member having another face opposite to said operating face, a bar member xed to said other face and elongated in a direction away from said blade member, a bracket xedly mounted on a portion of said bar member remote from said other face, two pivots securing said arm and one of said abutments to said bracket for respective pivoting movements about said second axis and about a third axis offset from said second axis transversely to the direction of elongation of said arm.

8. In an arrangement as set forth in claim 7, means on said bracket for limiting movement of said arm about said second axis away from a position in which said bar member and said arm are longitudinally aligned.

References Cited UNITED STATES PATENTS 3,022,835 2/1962' Jennings 172269 2,166,424 7/1939 Coates 37-42 VL 3,302,728 2/1967 Sullivan et al. 172-269 FOREIGN PATENTS 547,201 10/1957 Canada 172f-269 1,443,289 5/1966 France 172--269 ROBERT E. PULFREY, Primary Examiner R. E. SUTER, Assistant Examiner U.S. Cl. X.R. 172--269 

